Low Power Chaining

ABSTRACT

A group of low power transceiver devices may create a private wireless network. In a private communication network, each device may monitor neighboring devices and transmit a low power signal on a periodic basis. At any time, if a device breaks away from the private communication network, the device determines its location and then transmits its location to one or more devices in the group at a high transmit power level.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation U.S. patent application Ser. No.14/534,424 filed Nov. 6, 2014, which is incorporated herein by referencein its entirety.

TECHNICAL FIELD

The technical field generally relates to wireless communications andmore specifically to peer-to-peer communication.

BACKGROUND

Adventure sports like mountaineering, diving, snow skiing, fast-packing,ultra-marathoning, and others involve individuals taking on risks ofinjury, sickness, disorientation, and ultimately getting lost from thelarger group of participants. In cases such as mountaineering anddiving, as examples, the existence of macro cellular networks is minimalto non-existent due to the location. Conventional technology may enableshort distance communication through handheld CB radio, but thesetechnologies require operation by the participant who often is insituations where they are unable to respond (in the case of injury,sickness, or disorientation).

SUMMARY

The following presents a simplified summary that describes some aspectsexample of the subject disclosure. This summary is not an extensiveoverview of the disclosure. Indeed, additional or alternative aspectsand/or examples of the subject disclosure may be available beyond thosedescribed in the summary.

Discussed herein is the use of a group of low power transceiver devicesthat can create a private wireless network. A method may comprisetransmitting, by a first device, a first signal at a first transmitpower, the first signal indicative of a status of the first device;searching, by the first device, for a second signal of a second device,the second signal indicative of a status of the second device;determining, by the first device, that the second signal from the seconddevice has not been detected within a first period; responsive to thedetermining that the second signal from the second device has not beendetected within the first period, determining a location of the firstdevice; and transmitting by the first device, at a second transmitpower, an alert to the second device, the alert comprising the location.

In another example, a mobile device may comprise a processor coupledwith a memory. The memory may have stored thereon executableinstructions that when executed by the processor cause the processor toeffectuate operations comprising: transmitting a first signal at a firsttransmit power, the first signal indicative of a status of the mobiledevice; searching for a second signal of a second device, the secondsignal indicative of a status of the second device; determining that thesignal from the second device has not been detected within a firstperiod; responsive to the determining that the signal from the seconddevice has not been detected within the first period, determining alocation of the mobile device; and transmitting at a second transmitpower, an alert, the alert comprising the location.

In another example, there may be a system that includes a first devicecoupled with a second device. A memory of the first device may havestored thereon executable instructions that when executed by a processorcause the processor to effectuate operations comprising: transmitting afirst signal at a first transmit power, the first signal indicative of astatus of the first device; searching for a second signal of a seconddevice, the second signal indicative of a status of the second device;determining that the signal from the second device has not been detectedwithin a first period; responsive to the determining that the signalfrom the second device has not been detected within the first period,determining a location of the first device; and transmitting at a secondtransmit power, an alert, the alert comprising the location.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description is better understood when read inconjunction with the appended drawings. For the purposes ofillustration, exemplary examples are shown in the drawings; however, thesubject matter is not limited to the specific elements andinstrumentalities disclosed. In the drawings:

FIG. 1 illustrates an exemplary system for implementing low powerchaining;

FIG. 2 illustrates an exemplary method for implementing low powerchaining;

FIG. 3 illustrates an exemplary tree system for implementing low powerchaining;

FIG. 4 illustrates an exemplary linear system for implementing low powerchaining;

FIG. 5 illustrates an exemplary method for configuring low powerchaining;

FIG. 6 is a block diagram of a non-limiting exemplary mobile device inwhich one or more disclosed examples may be implemented for low powerchaining;

FIG. 7 is a block diagram of a non-limiting exemplary processor in whichone or more disclosed examples may be implemented for low powerchaining;

FIG. 8 is a block diagram of a non-limiting exemplary packet-basedmobile cellular network environment, such as a GPRS network, in whichone or more disclosed examples may be implemented for low powerchaining;

FIG. 9 illustrates a non-limiting exemplary architecture of a typicalGPRS network, segmented into four groups, in which one or more disclosedexamples may be implemented for low power chaining;

FIG. 10 illustrates a non-limiting alternate block diagram of anexemplary GSM/GPRS/IP multimedia network architecture in which one ormore disclosed examples may be implemented for low power chaining; and

FIG. 11 illustrates a Public Land Mobile Network (PLMN) block diagramview of an exemplary architecture in which one or more disclosedexamples may be implemented for low power chaining.

DETAILED DESCRIPTION

Discussed herein is the use of a group (two or more) of low powertransceiver devices that can create a private wireless network. Eachdevice in the group may look for a signal of a neighboring device andtransmit a low power signal containing a beacon on a periodic basis. Inan example, the devices are paired (e.g., Bluetooth) with each other andwith a master device prior to the excursion. The use of low powerchaining may provide the ability to keep track of a group of devices.Each device may be associated with an individual or an object. Low powerchaining may be helpful during scenarios such as school children at anoffsite school field trip, elderly individuals on a shopping excursion,mountain climbing with a team, ocean diving with a team, and otherscenarios where a person, animal, or object has a risk of getting lost.It is contemplated that low power chaining may be associated withanything that is desired to be kept in proximity of like or unlikeobjects.

FIG. 1 illustrates an exemplary system for implementing low powerchaining. In FIG. 1, wireless transmit/receive unit (WTRU) 101 iscommunicatively connected with WTRU 103 and WTRU 105. WTRU 107 iscommunicatively connected with WTRU 105 and WTRU 103. WTRU 101, WTRU103, WTRU 105, and WTRU 107 are within group 100 and can communicate viapeer-to-peer communication. The arrangement of WTRUs within group 100 islogical and is not necessarily an indication of a physical position ofany one of the WTRUs. WTRU 101, WTRU 103, WTRU 105, and WTRU 107 may beany type of device configured to communicate in a wireless environment.By way of example, WTRU 101, WTRU 103, WTRU 105, or WTRU 107 may includeuser equipment (UE), a mobile station, a mobile device, a fixed ormobile subscriber unit, a pager, a cellular telephone, a personaldigital assistant (PDA), a smartphone, a laptop, a netbook, a personalcomputer, a wireless sensor, a smart watch, a printer, a display, atelevision, a consumer electronic, or the like. A WTRU as discussedherein may be a somewhat simplistic device, such as a bracelet or bandthat has a small or nonexistent interface display. The simplistic WTRUmay be configured for low power chaining by a more complex device suchas a mobile phone, tablet, or laptop. There may be a parent-childrelationship among the WTRU's in group 100. For example, WTRU 101, maybe called a parent WTRU and may configure and monitor the policies forWTRU 103, WTRU 105, and WTRU 107 with regard to low power chaining. As aparent WTRU, WTRU 101 may configure policies, such as a threshold fortransmitting an alert (e.g., an emergency alert), the acts that a WTRUmay take after the threshold has been reached, and what WTRUsproactively listen to other WTRUs, among other things.

Below are exemplary methods associated with low power chaining. Unlessspecifically stated, the method as shown below (e.g., FIG. 2 and FIG. 5)and those in other methods presented in the drawings or described arenot necessarily constrained to a particular order or sequence. FIG. 2illustrates an exemplary method 200 for implementing low power chaining.At block 201, WTRU 103 and the other WTRUs of group 100 may havepolicies for low power chaining configured by WTRU 101, which in thisexample, is a parent WTRU. WTRU 101 may instruct WTRU 103 to set aparticular transmit power level (e.g., less than 5% of max power level)and listen for and respond to different WTRUs. Each WTRU of group 100may have a different transmit power level based on user preferences,default configurations, or the like. In an example, in a field tripscenario, there may be a desire for a WTRU associated with a child(e.g., WTRU 103) to stay close to a WTRU associated with a chaperone(e.g., WTRU 101). A WTRU associated with another chaperone (e.g., WTRU107) may not need to be as close to the chaperone associated WTRU 101.WTRU 101 may instruct WTRU 103 to monitor an air interface for signalsfrom WTRU 107 and WTRU 101, as well as transmit a low power wirelesssignal (e.g., a beacon) to WTRU 107 and WTRU 101. WTRU 101 may instructWTRU 103 to monitor an air interface for a certain threshold period thattriggers an emergency state.

At block 202, WTRU 103 monitors an air interface for a signal fromanother WTRU (e.g., WTRU 101). The signal may carry a beacon, which maybe considered a relatively small packet with minimal information. WTRU103 and WTRU 101 may communicate with each other at a relatively lowpower level that may be detectable within a few meters (e.g., 5 meters).At block 203, WTRU 103 may determine that a signal has not arrived fromWTRU 101 within a threshold amount of time (e.g., 15 seconds) or at acertain time (e.g., 6 PM). WTRU 101 may have been powered off or theWTRU 103 and WTRU 101 may be out of range of each other for therelatively low power level. At block 205, WTRU 103 may determine itsapproximate location via an application, such as turning on and usingGPS. In another example with regard to determining location, WTRU 103may request from WTRU 107 the location of WTRU 107. WTRU 103 may thensubsequently extrapolate its location based on the response from WTRU107 (e.g., extrapolating a 5 meter radius from the received WTRU 107location that excludes the intersection of the radius around WTRU 103).

At block 207, WTRU 103 may transmit an alert at an increased powerlevel. WTRU 103 may transmit the alert in different ways, such astransmitting the alert to only WTRU 101, transmitting the alert to allWTRUs in its group 100 to transmit to WTRU 101, or transmitting (e.g.,broadcasting) the alert to all devices in the vicinity. The alert maycontain information, such as the location of WTRU 103 and the status ofWTRU 103 in relation to other devices (e.g., location and communicationstatus as associated with other devices). In an example, the alert maybe sent at a substantially higher transmit power level than waspreviously used (e.g., greater than 50% of a previously used transmitpower level). For instance with regard to the previous example, aninitial transmit power may be 7 dBm and may increase 50% toapproximately 10.5 dBm. In another example, the alert may be sent at orapproximate maximum transmit power level of WTRU 103 (e.g., greater thanor equal to 90% of the possible or recommended/regulatory transmit powerlevel of a device). In another example, WTRU 103 may continually send analert at a stepped up transmit power level until a particular responseis received from WTRU 101. For instance, WTRU 103 may send an initialalert at a first transmit power level (e.g., 20% of max transmit powerlevel) and then, if no response from WTRU 101, WTRU 103 may send asecond alert at a second transmit power level (e.g., 30% of max powerlevel), and so on.

At block 208, WTRU 101 (after realizing there is no signal between WTRU101 and WTRU 103) can instruct all WTRUs in group 100 to listen for atransmission from WTRU 103. At block 209, each WTRU that hears thetransmission reports back to WTRU 101. The reporting of block 209 may bethrough a chain of peep-to-peer connections (e.g., WTRU 107 to WTRU 105to WTRU 101). WTRU 101 may acknowledge receipt of the reporting WTRUsusing a maximum or approximately maximum transmit power. As discussed inmore detail herein, at block 210, WTRU 103 may continue to transmit analert until a satisfactory re-linking of WTRU 103 within group 100 hasoccurred. A satisfactory re-linking may be based on a policy configuredby parent WTRU 101. An example satisfactory re-linking may be differentfrom the previous group configuration, such as WTRU 103 linking with twoWTRUs in the group, such as WTRU 107 and WTRU 105. In this satisfactoryre-linking the transmit power level may be different from a previous(e.g., initially provisioned) transmit power level.

FIG. 3 and FIG. 4 are different logical configurations of a group ofWTRUs that employs low power chaining. Some or all of the method of FIG.2 may be implemented in the architecture as shown and described for FIG.3 and FIG. 4. With regard to FIG. 3, WTRU 111 is a parent device and theother devices in group 110 are child WTRUs. As shown in FIG. 3, theremay be different sub-groups (group 114, group 118, and group 122), whichmay help isolate any broadcasts when there is an emergency state. Inthis configuration, parent WTRU 111 only immediately monitors its linksto WTRU 113, WTRU 117, and WTRU 121. If WTRU 111 is notified of anemergency state, such as link 112 being disconnected, WTRU 111 mayinitially address alerts to WTRUs of group 114 and group 118, until athreshold time period passes that calls for the involvement of the WTRUsof group 122.

FIG. 4 is another illustration of a configuration for low powerchaining. Here, during a non-emergency state, the WTRU's in group 130are transmitting to and listening for one or two WTRUs. WTRU 131 maymaintain an active connection with cellular network 132 while the otherWTRUs of group 130 only maintain a low power chaining connection (e.g.,no cellular or no other wireless connection). WTRU 133, WTRU 135, WTRU137, and WTRU 139 may periodically report the status of any peep-to-peerconnections up the chain to WTRU 131. The status may be as simple as anindicator of a positive or negative status between the appropriate WTRUin group 130. WTRU 131 may periodically report the status of the groupas well as its own GPS location to low power chaining server 134. Thelocation of the other WTRUs may be extrapolated based on the GPSlocation of WTRU 131 and the status of the WTRUs in group 130. Low powerchaining server 134 may report alerts to the appropriate authorities(e.g., United States park police (USPP)). The alerts may be an indicatorof a situation that requires immediate assistance (an emergency) or anindicator that an area should be proactively patrolled. Low powerchaining server 134 may also have authorization to initially provide orupdate policies to the WTRUs of group 130. For example, a policy maychange based on the location (e.g., a challenging terrain) so that WTRUsof group 130 are instructed to be closer together or allowed to befarther apart before an alert is triggered.

FIG. 5 illustrates an exemplary method for activating low power chainingon a WTRU. At block 221, a low power chaining mode may be selected on aWTRU. At block 223, subsequent to the low power chaining mode beingselected, a group, which has other WTRUs, may be selected for the WTRUto join in low power chaining. At block 225, after the group is selecteda policy that corresponds to the selected group of block 225 may beconfigured onto the WTRU. The policy may include turning off allwireless connections except for the wireless connection that will beused for the low power chaining. The wireless connection may be anywireless connection, such as WiFi, Bluetooth, Zigbee, or cellular.

FIG. 6 illustrates an example wireless device 1010 (i.e., WTRU) that maybe used in connection with an example of low power chaining. Referenceswill also be made to other figures of the present disclosure asappropriate. For example, mobile devices, such as WTRU 102, WTRU 103,and WTRU 107 may be wireless devices of the type described in regard toFIG. 6, and may have some, all, or none of the components and modulesdescribed in regard to FIG. 6. It will be appreciated that thecomponents and modules of wireless device 1010 illustrated in FIG. 6 areillustrative, and that any number and type of components and/or modulesmay be present in wireless device 1010. In addition, the functionsperformed by any or all of the components and modules illustrated inFIG. 6 may be performed by any number of physical components. Thus, itis possible that in some examples the functionality of more than onecomponent and/or module illustrated in FIG. 4 may be performed by anynumber or types of hardware or hardware and software.

Processor 1021 may comprise any appropriate circuitry that performsoperations on behalf of wireless device 1010. Such circuitry may includehardware and other components that enable processor 1021 to perform anyof the functions and methods described herein. Such circuitry and othercomponents may also enable processor 1021 to communicate and/or interactwith other devices and components, for example any other component ofdevice of wireless device 1010, in such a manner as to enable processor118 and such other devices and/or components to perform any of thedisclosed functions and methods. In one example, processor 1021 executessoftware (i.e., computer readable instructions stored in a computerreadable medium) that may include functionality related to low powerchaining, for example. User interface module 1022 may be any type orcombination of hardware and software that enables a user to operate andinteract with wireless device 1010, and, in one example, to interactwith a system enabling the user to place, request, and/or receive calls,text communications of any type, voicemail, voicemail notifications,voicemail content and/or data, and/or a system. For example, userinterface module 1022 may include a display, physical and/or “soft”keys, voice recognition software, a microphone, a speaker and the like.Wireless communication module 1023 may be any type of transceiverincluding any combination of hardware and software that enables wirelessdevice 1010 to communicate with wireless network equipment. Memory 1024enables wireless device 1010 to store information, such as APNs, MNCs,MCCs, text communications content and associated data, multimediacontent, software to efficiently process radio resource requests andservice requests, and radio resource request processing preferences andconfigurations. Memory 1024 may take any form, such as internal randomaccess memory (RAM), an SD card, a microSD card and the like. Powersupply 1025 may be a battery or other type of power input (e.g., acharging cable that is connected to an electrical outlet, etc.) that iscapable of powering wireless device 1010. SIM 1026 may be any typeSubscriber Identity Module and may be configured on a removable ornon-removable SIM card that allows wireless device 1010 to store data onSIM 1026.

FIG. 7 is a block diagram of an example apparatus 1158 which may beemployed in any of the examples described herein, including as one ormore components of WTRU 556, WTRU 103, and WTRU 107, as one or morecomponents of low power chaining server 134, and/or any relatedequipment, and/or as one or more components of any third party system orsubsystem that may implement any portion of the subject matter describedherein. Apparatus 1158 may be a processor. It is emphasized that theblock diagram depicted in FIG. 7 is exemplary and not intended to implya specific implementation. Thus, the apparatus 1158 may be implementedin a single processor or multiple processors. Multiple processors may bedistributed or centrally located. Multiple processors can communicatewirelessly, via hard wire, or a combination thereof. Apparatus 1158 mayinclude circuitry and other components that enable apparatus 1158 toperform any of the functions and methods described herein. Suchcircuitry and other components may also enable apparatus 1158 tocommunicate and/or interact with other devices and components, forexample any other component of any device disclosed herein or any otherdevice, in such a manner as to enable apparatus 1158 and such otherdevices and/or components to perform any of the disclosed functions andmethods.

As depicted in FIG. 7, the apparatus 1158 may comprise a processingportion 1160, a memory portion 1162, and an input/output portion 1164.The processing portion 1160, memory portion 1162, and input/outputportion 1164 are coupled together (coupling not shown in FIG. 7) toallow communications between these portions. The input/output portion1164 is capable of providing and/or receiving components, commands,and/or instructions, utilized to, for example, request and receive APNs,MNCs, and/or MCCs, establish and terminate communications sessions,transmit and receive service requests and data access request data andresponses, transmit, receive, store and process text, data, and voicecommunications, execute software that efficiently processes radioresource requests, receive and store service requests and radio resourcerequests, radio resource request processing preferences andconfigurations, and/or perform any other function described herein.

The apparatus 1158 may be implemented as a client processor and/or aserver processor. In a basic configuration, the apparatus 1158 mayinclude at least one processing portion 1160 and memory portion 1162.The memory portion 1162 can store any information utilized inconjunction with establishing, transmitting, receiving, and/orprocessing text, data, and/or voice communications,communications-related data and/or content, voice calls, othertelephonic communications, etc. For example, the memory portion iscapable of storing APNs, MNCs, MCCs, service requests, radio resourcerequests, QoS and/or APN parameters, software for low power chaining,text and data communications, calls, voicemail, multimedia content,visual voicemail applications, etc. Depending upon the exactconfiguration and type of processor, the memory portion 1162 can bevolatile (such as RAM) 1166, non-volatile (such as ROM, flash memory,etc.) 1168, or a combination thereof. The apparatus 1158 can haveadditional features/functionality. For example, the apparatus 1158 mayinclude additional storage (removable storage 1170 and/or non-removablestorage 1172) including, but not limited to, magnetic or optical disks,tape, flash, smart cards or a combination thereof. Computer storagemedia, such as memory and storage elements 1162, 1170, 1172, 1166, and1168, may include volatile and nonvolatile, removable and non-removablemedia implemented in any method or technology for storage of informationsuch as computer readable instructions, data structures, programmodules, or other data. Computer storage media include, but are notlimited to, RAM, ROM, EEPROM, flash memory or other memory technology,CD-ROM, digital versatile disks (DVD) or other optical storage, magneticcassettes, magnetic tape, magnetic disk storage or other magneticstorage devices, universal serial bus (USB) compatible memory, smartcards, or any other medium that can be used to store the desiredinformation and that can be accessed by the apparatus 1158. Any suchcomputer storage media may be part of the apparatus 1158.

The apparatus 1158 may also contain the communications connection(s)1180 that allow the apparatus 1158 to communicate with other devices,for example through a radio access network (RAN). Communicationsconnection(s) 1180 is an example of communication media. Communicationmedia typically embody computer-readable instructions, data structures,program modules or other data in a modulated data signal such as acarrier wave or other transport mechanism and includes any informationdelivery media. The term “modulated data signal” means a signal that hasone or more of its characteristics set or changed in such a manner as toencode information in the signal. By way of example, and not limitation,communication media includes wired media such as a wired network ordirect-wired connection as might be used with a land line telephone, andwireless media such as acoustic, RF, infrared, cellular, and otherwireless media. The term computer-readable media as used herein includesboth storage media and communication media. The apparatus 1158 also canhave input device(s) 1176 such as keyboard, keypad, mouse, pen, voiceinput device, touch input device, etc. Output device(s) 1174 such as adisplay, speakers, printer, etc. also can be included.

A RAN as described herein may comprise any telephony radio network, orany other type of communications network, wireline or wireless, or anycombination thereof. The following description sets forth some exemplarytelephony radio networks, such as the global system for mobilecommunications (GSM), and non-limiting operating environments. Thebelow-described operating environments should be considerednon-exhaustive, however, and thus the below-described networkarchitectures merely show how low power chaining may be implemented withstationary and non-stationary network structures and architectures inorder to do low power chaining. It can be appreciated, however, that lowpower chaining as described herein may be incorporated with existingand/or future alternative architectures for communication networks aswell.

The GSM is one of the most widely utilized wireless access systems intoday's fast growing communication environment. The GSM providescircuit-switched data services to subscribers, such as mobile telephoneor computer users. The General Packet Radio Service (GPRS), which is anextension to GSM technology, introduces packet switching to GSMnetworks. The GPRS uses a packet-based wireless communication technologyto transfer high and low speed data and signaling in an efficientmanner. The GPRS attempts to optimize the use of network and radioresources, thus enabling the cost effective and efficient use of GSMnetwork resources for packet mode applications.

The exemplary GSM/GPRS environment and services described herein alsomay be extended to 3G services, such as Universal Mobile TelephoneSystem (UMTS), Frequency Division Duplexing (FDD) and Time DivisionDuplexing (TDD), High Speed Packet Data Access (HSPDA), cdma2000 1Evolution Data Optimized (EVDO), Code Division Multiple Access-2000(cdma2000 3), Time Division Synchronous Code Division Multiple Access(TD-SCDMA), Wideband Code Division Multiple Access (WCDMA), EnhancedData GSM Environment (EDGE), International MobileTelecommunications-2000 (IMT-2000), Digital Enhanced CordlessTelecommunications (DECT), 4G Services such as Long Term Evolution(LTE), etc., as well as to other network services that become availablein time. In this regard, low power chaining may be applied independentlyof the method of data transport and does not depend on any particularnetwork architecture or underlying protocols.

FIG. 8 depicts an overall block diagram of an exemplary packet-basedmobile cellular network environment, such as a GPRS network, in whichlow power chaining systems and methods such as those described hereinmay be practiced. In an example configuration, any RAN as describedherein may be encompassed by or interact with the network environmentdepicted in FIG. 8. Similarly, mobile devices, such as WTRU 102, WTRU103, and WTRU 107 may communicate or interact with a network environmentsuch as that depicted in FIG. 8. In such an environment, there may be aplurality of Base Station Subsystems (BSS) 900 (only one is shown), eachof which comprises a Base Station Controller (BSC) 902 serving aplurality of Base Transceiver Stations (BTS) such as BTSs 904, 906, and908. BTSs 904, 906, 908, etc. are the access points where users ofpacket-based mobile devices (e.g., WTRU 102, WTRU 103, and WTRU 107)become connected to the wireless network. In exemplary fashion, thepacket traffic originating from user devices (e.g., WTRU 102, WTRU 103,and WTRU 107) may be transported via an over-the-air interface to a BTS908, and from the BTS 908 to the BSC 902. Base station subsystems, suchas BSS 900, may be a part of internal frame relay network 910 that caninclude Service GPRS Support Nodes (SGSN) such as SGSN 912 and 914. EachSGSN may be connected to an internal packet network 920 through which aSGSN 912, 914, etc. may route data packets to and from a plurality ofgateway GPRS support nodes (GGSN) 922, 924, 926, etc. As illustrated,SGSN 914 and GGSNs 922, 924, and 926 may be part of internal packetnetwork 920. Gateway GPRS serving nodes 922, 924 and 926 may provide aninterface to external Internet Protocol (IP) networks, such as PublicLand Mobile Network (PLMN) 950, corporate intranets 940, or Fixed-EndSystem (FES) or the public Internet 930. As illustrated, subscribercorporate network 940 may be connected to GGSN 924 via firewall 932, andPLMN 950 may be connected to GGSN 924 via border gateway router 934. TheRemote Authentication Dial-In User Service (RADIUS) server 942 may beused for caller authentication when a user of a mobile cellular devicecalls corporate network 940.

Generally, there can be four different cell sizes in a GSM network,referred to as macro, micro, pico, and umbrella cells. The coverage areaof each cell is different in different environments. Macro cells may beregarded as cells in which the base station antenna is installed in amast or a building above average roof top level. Micro cells are cellswhose antenna height is under average roof top level. Micro-cells may betypically used in urban areas. Pico cells are small cells having adiameter of a few dozen meters. Pico cells may be used mainly indoors.On the other hand, umbrella cells may be used to cover shadowed regionsof smaller cells and fill in gaps in coverage between those cells.

FIG. 9 illustrates an architecture of a typical GPRS network segmentedinto four groups: users 1050, radio access network 1060, core network1070, and interconnect network 1080. Users 1050 may comprise a pluralityof end users (though only mobile subscriber 1055 is shown in FIG. 9). Inan example, the device depicted as mobile subscriber 1055 may compriseany of mobile devices WTRU 102, WTRU 103, and WTRU 107. Radio accessnetwork 1060 comprises a plurality of base station subsystems such asBSSs 1062, which include BTSs 1064 and BSCs 1066. Core network 1070comprises a host of various network elements. As illustrated here, corenetwork 1070 may comprise Mobile Switching Center (MSC) 1071, ServiceControl Point (SCP) 1072, gateway MSC 1073, SGSN 1076, Home LocationRegister (HLR) 1074, Authentication Center (AuC) 1075, Domain NameServer (DNS) 1077, and GGSN 1078. Interconnect network 1080 may alsocomprise a host of various networks and other network elements. Asillustrated in FIG. 9, interconnect network 1080 comprises PublicSwitched Telephone Network (PSTN) 1082, Fixed-End System (FES) orInternet 1084, firewall 1088, and Corporate Network 1089.

A mobile switching center may be connected to a large number of basestation controllers. At MSC 1071, for instance, depending on the type oftraffic, the traffic may be separated in that voice may be sent toPublic Switched Telephone Network (PSTN) 1082 through Gateway MSC (GMSC)1073, and/or data may be sent to SGSN 1076 that may send the datatraffic to GGSN 1078 for further forwarding.

When MSC 1071 receives call traffic, for example, from BSC 1066, it maysend a query to a database hosted by SCP 1072. The SCP 1072 may processthe request and may issue a response to MSC 1071 so that it may continuecall processing as appropriate.

The HLR 1074 may be a centralized database for users to register to theGPRS network. In some examples, HLR 1074 may be a device such as HSSs.HLR 1074 may store static information about the subscribers such as theInternational Mobile Subscriber Identity (IMSI), APN profiles asdescribed herein, subscribed services, and a key for authenticating thesubscriber. HLR 1074 may also store dynamic subscriber information suchas dynamic APN profiles and the current location of the mobilesubscriber. HLR 1074 may also serve to intercept and determine thevalidity of destination numbers in messages sent from a device, such asmobile subscriber 1055, as described herein. Associated with HLR 1074may be AuC 1075. AuC 1075 may be a database that contains the algorithmsfor authenticating subscribers and may include the associated keys forencryption to safeguard the user input for authentication.

In the following, depending on context, the term “mobile subscriber”sometimes refers to the end user and sometimes to the actual portabledevice, such as WTRU 102, WTRU 103, and WTRU 107, used by an end user ofa mobile cellular service or a wireless provider. When a mobilesubscriber turns on his or her mobile device, the mobile device may gothrough an attach process by which the mobile device attaches to an SGSNof the GPRS network. In FIG. 9, when mobile subscriber 1055 initiatesthe attach process by turning on the network capabilities of the mobiledevice, an attach request may be sent by mobile subscriber 1055 to SGSN1076. The SGSN 1076 queries another SGSN, to which mobile subscriber1055 was attached before, for the identity of mobile subscriber 1055.Upon receiving the identity of mobile subscriber 1055 from the otherSGSN, SGSN 1076 may request more information from mobile subscriber1055. This information may be used to authenticate mobile subscriber1055 to SGSN 1076 by HLR 1074. Once verified, SGSN 1076 sends a locationupdate to HLR 1074 indicating the change of location to a new SGSN, inthis case SGSN 1076. HLR 1074 may notify the old SGSN, to which mobilesubscriber 1055 was attached before, to cancel the location process formobile subscriber 1055. HLR 1074 may then notify SGSN 1076 that thelocation update has been performed. At this time, SGSN 1076 sends anAttach Accept message to mobile subscriber 1055, which in turn sends anAttach Complete message to SGSN 1076.

After attaching itself to the network, mobile subscriber 1055 may thengo through the authentication process. In the authentication process,SGSN 1076 may send the authentication information to HLR 1074, which maysend information back to SGSN 1076 based on the user profile that waspart of the user's initial setup. The SGSN 1076 may then send a requestfor authentication and ciphering to mobile subscriber 1055. The mobilesubscriber 1055 may use an algorithm to send the user identification(ID) and password to SGSN 1076. The SGSN 1076 may use the same algorithmand compares the result. If a match occurs, SGSN 1076 authenticatesmobile subscriber 1055.

Next, the mobile subscriber 1055 may establish a user session with thedestination network, corporate network 1089, by going through a PacketData Protocol (PDP) activation process. Briefly, in the process, mobilesubscriber 1055 may request access to an Access Point Name (APN), forexample, UPS.com, and SGSN 1076 may receive the activation request frommobile subscriber 1055. SGSN 1076 may then initiate a Domain NameService (DNS) query to learn which GGSN node has access to the UPS.comAPN. The DNS query may be sent to the DNS server within the core network1070, such as DNS 1077, which may be provisioned to map to one or moreGGSN nodes in the core network 1070. Based on the APN, the mapped GGSN1078 may access the requested corporate network 1089. The SGSN 1076 maythen send to GGSN 1078 a Create Packet Data Protocol (PDP) ContextRequest message that contains necessary information. The GGSN 1078 maysend a Create PDP Context Response message to SGSN 1076, which may thensend an Activate PDP Context Accept message to mobile subscriber 1055.

Once activated, data packets of the call made by mobile subscriber 1055may then go through radio access network 1060, core network 1070, andinterconnect network 1080, in a particular fixed-end system, or Internet1084 and firewall 1088, to reach corporate network 1089.

Thus, network elements that can invoke the functionality of low powerchaining systems and methods such as those described herein may include,but are not limited to, Gateway GPRS Support Node tables, Fixed EndSystem router tables, firewall systems, VPN tunnels, and any number ofother network elements as required by the particular digital network.

FIG. 10 illustrates another exemplary block diagram view of aGSM/GPRS/IP multimedia network architecture 1100 in which the systemsand methods for low power chaining such as those described herein may beincorporated. As illustrated, architecture 1100 of FIG. 10 includes aGSM core network 1101, a GPRS network 1130 and an IP multimedia network1138. The GSM core network 1101 includes a Mobile Station (MS) 1102, atleast one Base Transceiver Station (BTS) 1104 and a Base StationController (BSC) 1106. The MS 1102 is physical equipment or MobileEquipment (ME), such as a mobile telephone or a laptop computer (e.g.,WTRU 102, WTRU 103, and WTRU 107) that is used by mobile subscribers, inone example with a Subscriber identity Module (SIM). The SIM includes anInternational Mobile Subscriber Identity (IMSI), which is a uniqueidentifier of a subscriber. The SIM may also include APNs. The BTS 1104may be physical equipment, such as a radio tower, that enables a radiointerface to communicate with the MS. Each BTS may serve more than oneMS. The BSC 1106 may manage radio resources, including the BTS. The BSCmay be connected to several BTSs. The BSC and BTS components, incombination, are generally referred to as a base station (BSS) or radioaccess network (RAN) 1103.

The GSM core network 1101 may also include a Mobile Switching Center(MSC) 1108, a Gateway Mobile Switching Center (GMSC) 1110, a HomeLocation Register (HLR) 1112, Visitor Location Register (VLR) 1114, anAuthentication Center (AuC) 1118, and an Equipment Identity Register(EIR) 1116. The MSC 1108 may perform a switching function for thenetwork. The MSC may also perform other functions, such as registration,authentication, location updating, handovers, and call routing. The GMSC1110 may provide a gateway between the GSM network and other networks,such as an Integrated Services Digital Network (ISDN) or Public SwitchedTelephone Networks (PSTNs) 1120. Thus, the GMSC 1110 providesinterworking functionality with external networks.

The HLR 1112 may be a database that may contain administrativeinformation regarding each subscriber registered in a corresponding GSMnetwork. Such information may include APNs and APN profiles. The HLR1112 may also contain the current location of each MS. The VLR 1114 maybe a database that contains selected administrative information from theHLR 1112. The VLR may contain information necessary for call control andprovision of subscribed services for each MS currently located in ageographical area controlled by the VLR. The HLR 1112 and the VLR 1114,together with the MSC 1108, may provide the call routing and roamingcapabilities of GSM. The AuC 1116 may provide the parameters needed forauthentication and encryption functions. Such parameters allowverification of a subscriber's identity. The EIR 1118 may storesecurity-sensitive information about the mobile equipment.

A Short Message Service Center (SMSC) 1109 allows one-to-one shortmessage service (SMS), or multimedia message service (MMS), messages tobe sent to/from the MS 1102. A Push Proxy Gateway (PPG) 1111 is used to“push” (i.e., send without a synchronous request) content to the MS1102. The PPG 1111 acts as a proxy between wired and wireless networksto facilitate pushing of data to the MS 1102. A Short Message Peer toPeer (SMPP) protocol router 1113 may be provided to convert SMS-basedSMPP messages to cell broadcast messages. SMPP is a protocol forexchanging SMS messages between SMS peer entities such as short messageservice centers. The SMPP protocol is often used to allow third parties,e.g., content suppliers such as news organizations, to submit bulkmessages.

To gain access to GSM services, such as voice, data, short messageservice (SMS), and multimedia message service (MMS), the MS may firstregister with the network to indicate its current location by performinga location update and IMSI attach procedure. MS 1102 may send a locationupdate including its current location information to the MSC/VLR, viaBTS 1104 and BSC 1106. The location information may then be sent to theMS's HLR. The HLR may be updated with the location information receivedfrom the MSC/VLR. The location update may also be performed when the MSmoves to a new location area. Typically, the location update may beperiodically performed to update the database as location updatingevents occur.

GPRS network 1130 may be logically implemented on the GSM core networkarchitecture by introducing two packet-switching network nodes, aserving GPRS support node (SGSN) 1132, a cell broadcast and a GatewayGPRS support node (GGSN) 1134. The SGSN 1132 may be at the samehierarchical level as the MSC 1108 in the GSM network. The SGSN maycontrol the connection between the GPRS network and the MS 1102. TheSGSN may also keep track of individual MS's locations and securityfunctions and access controls.

Cell Broadcast Center (CBC) 1133 may communicate cell broadcast messagesthat are typically delivered to multiple users in a specified area. CellBroadcast is one-to-many geographically focused service. It enablesmessages to be communicated to multiple mobile telephone customers whoare located within a given part of its network coverage area at the timethe message is broadcast.

GGSN 1134 may provide a gateway between the GPRS network and a publicpacket network (PDN) or other IP networks 1136. That is, the GGSN mayprovide interworking functionality with external networks, and set up alogical link to the MS through the SGSN. When packet-switched dataleaves the GPRS network, it may be transferred to an external TCP-IPnetwork 1136, such as an X.25 network or the Internet. In order toaccess GPRS services, the MS first attaches itself to the GPRS networkby performing an attach procedure. The MS then activates a packet dataprotocol (PDP) context, thus activating a packet communication sessionbetween the MS, the SGSN, and the GGSN.

In a GSM/GPRS network, GPRS services and GSM services may be used inparallel. The MS may operate in one three classes: class A, class B, andclass C. A class A MS may attach to the network for both GPRS servicesand GSM services simultaneously. A class A MS may also supportsimultaneous operation of GPRS services and GSM services. For example,class A mobiles may receive GSM voice/data/SMS calls and GPRS data callsat the same time.

A class B MS may attach to the network for both GPRS services and GSMservices simultaneously. However, a class B MS does not supportsimultaneous operation of the GPRS services and GSM services. That is, aclass B MS can only use one of the two services at a given time.

A class C MS can attach for only one of the GPRS services and GSMservices at a time. Simultaneous attachment and operation of GPRSservices and GSM services is not possible with a class C MS.

GPRS network 1130 may be designed to operate in three network operationmodes (NOM1, NOM2 and NOM3). A network operation mode of a GPRS networkmay be indicated by a parameter in system information messagestransmitted within a cell. The system information messages may direct anMS where to listen for paging messages and how to signal towards thenetwork. The network operation mode represents the capabilities of theGPRS network. In a NOM1 network, a MS may receive pages from a circuitswitched domain (voice call) when engaged in a data call. The MS maysuspend the data call or take both simultaneously, depending on theability of the MS. In a NOM2 network, a MS may not receive pages from acircuit switched domain when engaged in a data call, since the MS may bereceiving data and may not be listening to a paging channel. In a NOM3network, a MS may monitor pages for a circuit switched network whilereceiving data and vice versa.

The IP multimedia network 1138 was introduced with 3GPP Release 5, andmay include IP multimedia subsystem (IMS) 1140 to provide richmultimedia services to end users. A representative set of the networkentities within IMS 1140 are a call/session control function (CSCF), amedia gateway control function (MGCF) 1146, a media gateway (MGW) 1148,and a master subscriber database, called a home subscriber server (HSS)1150. HSS 1150 may be common to GSM core network 1101, GPRS network 1130as well as IP multimedia network 1138. HSS 1150 may include multipleHSSs.

IP multimedia system 1140 may be built around the call/session controlfunction, of which there are three types: an interrogating CSCF (I-CSCF)1143, a proxy CSCF (P-CSCF) 1142, and a serving CSCF (S-CSCF) 1144. TheP-CSCF 1142 is the MS's first point of contact with the IMS 1140. TheP-CSCF 1142 may forward session initiation protocol (SIP) messagesreceived from the MS to an SIP server in a home network (and vice versa)of the MS. The P-CSCF 1142 may also modify an outgoing request accordingto a set of rules defined by the network operator (for example, addressanalysis and potential modification).

I-CSCF 1143 forms an entrance to a home network and hides the innertopology of the home network from other networks and providesflexibility for selecting an S-CSCF. I-CSCF 1143 may contact subscriberlocation function (SLF) 1145 to determine which HSS 1150 to use for theparticular subscriber, if multiple HSSs 1150 are present. S-CSCF 1144may perform the session control services for MS 1102. This includesrouting originating sessions to external networks and routingterminating sessions to visited networks. S-CSCF 1144 may also decidewhether an application server (AS) 1152 is required to receiveinformation on an incoming SIP session request to ensure appropriateservice handling. This decision may be based on information receivedfrom HSS 1150 (or other sources, such as application server 1152). AS1152 may also communicate to location server 1156 (e.g., a GatewayMobile Location Center (GMLC)) that provides a position (e.g.,latitude/longitude coordinates) of MS 1102.

HSS 1150 may contain a subscriber profile and keep track of which corenetwork node is currently handling the subscriber. It may also supportsubscriber authentication and authorization functions (AAA). In networkswith more than one HSS 1150, a subscriber location function providesinformation on the HSS 1150 that contains the profile of a givensubscriber.

MGCF 1146 may provide interworking functionality between SIP sessioncontrol signaling from the IMS 1140 and ISUP/BICC call control signalingfrom the external GSTN networks (not shown.) It may also control themedia gateway (MGW) 1148 that provides user-plane interworkingfunctionality (e.g., converting between AMR- and PCM-coded voice.) MGW1148 may also communicate with other IP multimedia networks 1154.

Push to Talk over Cellular (PoC) capable mobile telephones may registerwith the wireless network when the telephones are in a predefined area(e.g., job site, etc.) When the mobile telephones leave the area, theymay register with the network in their new location as being outside thepredefined area. This registration, however, does not indicate theactual physical location of the mobile telephones outside thepre-defined area.

FIG. 11 illustrates a PLMN block diagram view of an exemplaryarchitecture in which low power chaining may be incorporated. MobileStation (MS) 1301 is the physical equipment used by the PLMN subscriber.In one illustrative example, communications device 40 may serve asMobile Station 1301. Mobile Station 1301 may be one of, but not limitedto, a cellular telephone, a cellular telephone in combination withanother electronic device or any other wireless mobile communicationdevice.

Mobile Station 1301 may communicate wirelessly with Base Station System(BSS) 1310. BSS 1310 contains a Base Station Controller (BSC) 1311 and aBase Transceiver Station (BTS) 1312. BSS 1310 may include a single BSC1311/BTS 1312 pair (Base Station) or a system of BSC/BTS pairs which arepart of a larger network. BSS 1310 is responsible for communicating withMobile Station 1301 and may support one or more cells. BSS 1310 isresponsible for handling cellular traffic and signaling between MobileStation 1301 and Core Network 1340. Typically, BSS 1310 performsfunctions that include, but are not limited to, digital conversion ofspeech channels, allocation of channels to mobile devices, paging, andtransmission/reception of cellular signals.

Additionally, Mobile Station 1301 may communicate wirelessly with RadioNetwork System (RNS) 1320. RNS 1320 contains a Radio Network Controller(RNC) 1321 and one or more Node(s) B 1322. RNS 1320 may support one ormore cells. RNS 1320 may also include one or more RNC 1321/Node B 1322pairs or alternatively a single RNC 1321 may manage multiple Nodes B1322. RNS 1320 is responsible for communicating with Mobile Station 1301in its geographically defined area. RNC 1321 is responsible forcontrolling the Node(s) B 1322 that are connected to it and is a controlelement in a UMTS radio access network. RNC 1321 performs functions suchas, but not limited to, load control, packet scheduling, handovercontrol, security functions, as well as controlling Mobile Station1301's access to the Core Network (CN) 1340.

The evolved UMTS Terrestrial Radio Access Network (E-UTRAN) 1330 is aradio access network that provides wireless data communications forMobile Station 1301 and User Equipment 1302. E-UTRAN 1330 provideshigher data rates than traditional UMTS. It is part of the Long TermEvolution (LTE) upgrade for mobile networks and later releases meet therequirements of the International Mobile Telecommunications (IMT)Advanced and are commonly known as a 4G networks. E-UTRAN 1330 mayinclude of series of logical network components such as E-UTRAN Node B(eNB) 1331 and E-UTRAN Node B (eNB) 1332. E-UTRAN 1330 may contain oneor more eNBs. User Equipment 1302 may be any user device capable ofconnecting to E-UTRAN 1330 including, but not limited to, a personalcomputer, laptop, mobile device, wireless router, or other devicecapable of wireless connectivity to E-UTRAN 1330. he improvedperformance of the E-UTRAN 1330 relative to a typical UMTS networkallows for increased bandwidth, spectral efficiency, and functionalityincluding, but not limited to, voice, high-speed applications, largedata transfer and IPTV, while still allowing for full mobility.

An exemplary mobile data and communication service that may beimplemented in the PLMN architecture described in FIG. 11 is theEnhanced Data rates for GSM Evolution (EDGE). EDGE is an enhancement forGPRS networks that implements an improved signal modulation scheme knownas 9-PSK (Phase Shift Keying). By increasing network utilization, EDGEmay achieve up to three times faster data rates as compared to a typicalGPRS network. EDGE may be implemented on any GSM network capable ofhosting a GPRS network, making it an ideal upgrade over GPRS since itmay provide increased functionality of existing network resources.Evolved EDGE networks are becoming standardized in later releases of theradio telecommunication standards, which provide for even greaterefficiency and peak data rates of up to 1 Mbit/s, while still allowingimplementation on existing GPRS-capable network infrastructure.

Typically Mobile Station 1301 may communicate with any or all of BSS1310, RNS 1320, or E-UTRAN 1330. In an illustrative system, each of BSS1310, RNS 1320, and E-UTRAN 1330 may provide Mobile Station 1301 withaccess to Core Network 1340. The Core Network 1340 may include of aseries of devices that route data and communications between end users.Core Network 1340 may provide network service functions to users in theCircuit Switched (CS) domain, the Packet Switched (PS) domain or both.The CS domain refers to connections in which dedicated network resourcesare allocated at the time of connection establishment and then releasedwhen the connection is terminated. The PS domain refers tocommunications and data transfers that make use of autonomous groupingsof bits called packets. Each packet may be routed, manipulated,processed or handled independently of all other packets in the PS domainand does not require dedicated network resources.

The Circuit Switched-Media Gateway Function (CS-MGW) 1341 is part ofCore Network 1340, and interacts with Visitor Location Register (VLR)and Mobile-Services Switching Center (MSC) Server 1360 and Gateway MSCServer 1361 in order to facilitate Core Network 1340 resource control inthe CS domain. Functions of CS-MGW 1341 include, but are not limited to,media conversion, bearer control, payload processing and other mobilenetwork processing such as handover or anchoring. CS-MGW 1340 mayreceive connections to Mobile Station 1301 through BSS 1310, RNS 1320 orboth.

Serving GPRS Support Node (SGSN) 1342 stores subscriber data regardingMobile Station 1301 in order to facilitate network functionality. SGSN1342 may store subscription information such as, but not limited to, theInternational Mobile Subscriber Identity (IMSI), temporary identities,or Packet Data Protocol (PDP) addresses. SGSN 1342 may also storelocation information such as, but not limited to, the Gateway GPRSSupport Node (GGSN) 1344 address for each GGSN where an active PDPexists. GGSN 1344 may implement a location register function to storesubscriber data it receives from SGSN 1342 such as subscription orlocation information.

Serving Gateway (S-GW) 1343 is an interface which provides connectivitybetween E-UTRAN 1330 and Core Network 1340. Functions of S-GW 1343include, but are not limited to, packet routing, packet forwarding,transport level packet processing, event reporting to Policy andCharging Rules Function (PCRF) 1350, and mobility anchoring forinter-network mobility. PCRF 1350 uses information gathered from S-GW1343, as well as other sources, to make applicable policy and chargingdecisions related to data flows, network resources and other networkadministration functions. Packet Data Network Gateway (PDN-GW) 1345 mayprovide user-to-services connectivity functionality including, but notlimited to, network-wide mobility anchoring, bearer session anchoringand control, and IP address allocation for PS domain connections.

Home Subscriber Server (HSS) 1363 is a database for user information,and stores subscription data regarding Mobile Station 1301 or UserEquipment 1302 for handling calls or data sessions. Networks may containone HSS 1363 or more if additional resources are required. Exemplarydata stored by HSS 1363 include, but is not limited to, useridentification, numbering and addressing information, securityinformation, or location information. HSS 1363 may also provide call orsession establishment procedures in both the PS and CS domains.

The VLR/MSC Server 1360 provides user location functionality. WhenMobile Station 1301 enters a new network location, it begins aregistration procedure. A MSC Server for that location transfers thelocation information to the VLR for the area. A VLR and MSC Server maybe located in the same computing environment, as is shown by VLR/MSCServer 1360, or alternatively may be located in separate computingenvironments. A VLR may contain, but is not limited to, user informationsuch as the IMSI, the Temporary Mobile Station Identity (TMSI), theLocal Mobile Station Identity (LMSI), the last known location of themobile station, or the SGSN where the mobile station was previouslyregistered. The MSC server may contain information such as, but notlimited to, procedures for Mobile Station 1301 registration orprocedures for handover of Mobile Station 1301 to a different section ofthe Core Network 1340. GMSC Server 1361 may serve as a connection toalternate GMSC Servers for other mobile stations in larger networks.

Equipment Identity Register (EIR) 1362 is a logical element which maystore the International Mobile Equipment Identities (IMEI) for MobileStation 1301. In a typical example, user equipment may be classified aseither “white listed” or “black listed” depending on its status in thenetwork. In one example, if Mobile Station 1301 is stolen and put to useby an unauthorized user, it may be registered as “black listed” in EIR1362, preventing its use on the network. Mobility Management Entity(MME) 1364 is a control node which may track Mobile Station 1301 or UserEquipment 1302 if the devices are idle. Additional functionality mayinclude the ability of MME 1364 to contact an idle Mobile Station 1301or User Equipment 1302 if retransmission of a previous session isrequired.

While examples of low power chaining have been described in connectionwith various communications devices and computing devices/processors,the underlying concepts can be applied to any communications orcomputing device, processor, or system capable of implementing the lowpower chaining systems and methods described. The various techniquesdescribed herein may be implemented in connection with hardware or acombination of hardware and software. Thus, low power chaining, orcertain aspects or portions thereof, may take the form of program code(i.e., instructions) embodied in tangible and/or media for persistentstorage (i.e., non-transitory media), such as floppy diskettes, CD-ROMs,hard drives, or any other machine-readable storage medium, wherein, whenthe program code is loaded into and executed by a machine, such as acomputer, the machine becomes an apparatus for low power chaining. Acomputer-readable storage medium, as described herein is an article ofmanufacture having a concrete, tangible, physical structure, and thus,not to be construed as a propagating signal. Any computer-readablestorage medium described herein is not to be construed as a signal. Anycomputer-readable storage medium described herein is to be construed asan article of manufacture having a concrete, tangible, physicalstructure. In the case of program code execution on programmablecomputers, the computing device will generally include a processor, astorage medium readable by the processor (including volatile andnon-volatile memory and/or storage elements), at least one input device,and at least one output device. The program(s) can be implemented inassembly or machine language, if desired. The language can be a compiledor interpreted language, and combined with hardware implementations. Thecomponents described herein are not software per se. The componentsdescribed herein are not software per se. A device may comprise aprocessor and memory, and the memory may include executable instructionsthat when executed by the processor cause the device to effectuateoperations, as described herein, to implement low power chaining.

Low power chaining also may be practiced via communications embodied inthe form of program code that is transmitted over some transmissionmedium, such as over electrical wiring or cabling, through fiber optics,or via any other form of transmission, wherein, when the program code isreceived, loaded into, and executed by a machine, such as an EPROM, agate array, a programmable logic device (PLD), a client computer, or thelike, the machine becomes an apparatus for low power chaining. Whenimplemented on a general-purpose processor, the program code combineswith the processor to provide a unique apparatus that operates to invokethe functionality of low power chaining as described herein.Additionally, any storage techniques used in connection with a low powerchaining system may invariably be a combination of hardware andsoftware.

While low power chaining has been described in connection with thevarious examples of the various figures, it is to be understood thatother similar examples may be used or modifications and additions may bemade to the described examples for performing the same function of lowpower chaining without deviating therefrom. For example, one skilled inthe art will recognize low power chaining as described in the presentapplication may apply to any environment, whether wired or wireless, andmay be applied to any number of such devices connected via acommunications network and interacting across the network. Therefore,low power chaining should not be limited to any single example, butrather should be construed in breadth and scope in accordance with theappended claims.

What is claimed:
 1. A computer readable storage medium comprisingcomputer executable instructions that when executed by a computingdevice cause said computing device to effectuate operations comprising:searching, by a first device, for a signal, the signal indicative of astatus of a second device; determining that the signal has not beendetected within a first period; and responsive to the determining thatthe signal has not been detected within the first period, determining alocation of the first device, and transmitting, at a first transmitpower, an alert comprising the location to the second device, the firsttransmit power greater than a second transmit power of the first period.2. The computer readable storage medium of claim 1, wherein the firsttransmit power is approximately a maximum transmit power of the firstdevice.
 3. The computer readable storage medium of claim 1, wherein thefirst transmit power is substantially higher than the second transmitpower.
 4. The computer readable storage medium of claim 1, whereindetermining of the location of the first device is based on a globalpositioning system of the first device, the global positioning system ofthe first device is activated responsive to the determining that thesignal from the second device has not been detected within the firstperiod, wherein the global positing system is not active during thefirst period.
 5. The computer readable storage medium of claim 1, theoperations further comprising: detecting, by the first device, thesignal from the second device; and deactivating a global position systemon the first device responsive to the detecting the signal from thesecond device.
 6. The computer readable storage medium of claim 1,wherein the determining of the location of the first device is based ona global positioning system of a third device.
 7. The computer readablestorage medium of claim 1, the operations further comprising:broadcasting the alert to a plurality of devices, the plurality ofdevices comprising the second device.
 8. A mobile device comprising: aprocessor; and a memory coupled with the processor, the memory havingstored thereon executable instructions that when executed by theprocessor cause the processor to effectuate operations comprising:searching for a signal, the signal indicative of a status of a firstdevice; determining that the signal has not been detected within a firstperiod; and responsive to the determining that the signal from the firstdevice has not been detected within the first period, determining alocation of the mobile device, and transmitting, at a first transmitpower, an alert comprising the location to the first device, the firsttransmit power greater than a second transmit power of the first period.9. The mobile device of claim 8, wherein the second transmit power isapproximately a maximum transmit power of the mobile device.
 10. Themobile device of claim 8, wherein the second transmit power issubstantially higher than the first transmit power.
 11. The mobiledevice of claim 8, wherein determining of the location of the mobiledevice is based on a global positioning system of the mobile device, theglobal positioning system of the mobile device is activated responsiveto the determining that the signal from the first device has not beendetected within the first period.
 12. The mobile device of claim 8,wherein the operations further comprise: detecting the signal from thefirst device; and deactivating a global position system on the mobiledevice based on the signal from the first device.
 13. The mobile deviceof claim 8, wherein the determining of the location of the mobile deviceis based on a global positioning system of a third device.
 14. Themobile device of claim 8, wherein the operations further comprise:broadcasting the alert to a plurality of devices, the plurality ofdevices comprising the first device.
 15. A method comprising: searching,by a first device, for a signal, the signal indicative of a status of asecond device; determining, by the first device, that the signal has notbeen detected within a first period; and responsive to the determiningthat the signal has not been detected within the first period,determining, by the first device, a location of the first device, andtransmitting, at a first transmit power by the first device, an alertcomprising the location to the second device, the first transmit powergreater than a second transmit power of the first period.
 16. The methodof claim 15, wherein the first transmit power is approximately a maximumtransmit power of the first device.
 17. The method of claim 15, whereinthe first transmit power is substantially higher than the secondtransmit power.
 18. The method of claim 15, wherein determining of thelocation of the first device is based on a global positioning system ofthe first device, the global positioning system of the first device isactivated responsive to the determining that the signal from the seconddevice has not been detected within the first period, wherein the globalpositing system is not active during the first period.
 19. The method ofclaim 15, further comprising: detecting, by the first device, the signalfrom the second device; and deactivating a global position system on thefirst device responsive to the detecting the signal from the seconddevice.
 20. The method of claim 15, further comprising: broadcasting thealert to a plurality of devices, the plurality of devices comprising thesecond device.